Effects of neurally adjusted ventilatory assist on subject-ventilator synchrony in rabbits with acute respiratory distress syndrome

Abstract

To observe the effects of neurally adjusted ventilatory assist (NAVA) on subject-ventilator synchrony in rabbits with acute respiratory distress syndrome (ARDS). The rabbit model of ARDS was induced by intratracheal infusion of hydrochloric acid. After sufficient recruitment, the rabbits were randomly divided into 2 groups: pressure support ventilation (PSV) group and NAVA group. The parameters of subject-ventilator synchrony such as ventilation trigger, ventilation switching and magnitude of assist were observed at 0, 1, 2, 3 h respectively. (1) Ventilation trigger: 1) trigger delay: the trigger delay in the NAVA group were markedly lower than the PSV group at 0, 1, 2, 3 h (P < 0.05); as ventilation time elapsed, the trigger delay changed neither in NAVA nor in PSV group (P > 0.05). 2) Ineffective trigger index: the ineffective trigger index was 17.7% ± 13.7% in the PSV group. While all neural efforts were trigger, there was no ineffective trigger observed in the NAVA group. (2) Off-cycle delay: the off-cycle delay were significantly lower in the PSV group than that in the NAVA group at 0, 1, 2, 3 h (P < 0.05); as the ventilation time elapsed, the off-cycle delay changed neither in the NAVA group nor in the PSV group (P > 0.05). (3) Magnitude of assist: in the NAVA group, peak EAdi and peak pressure were markedly correlated (determination coefficient 0.86 ± 0.07, P < 0.05). But pressure delivery during the PSV group was not correlated with EAdi (P > 0.05). As compared with PSV, NAVA can improve subject-ventilator synchrony in rabbits with ARDS.